GEOG1710 1st Edition Lecture 5 Outline of Previous Lecture I Earth s Energy Balance II Absorption III Thermal Energy IV Latent Heat and Sensible Heat Outline of Current Lecture I II III IV V Movement of Air Forces Wind Atmospheric Circulation Pressure Belts Current Lecture Movement of Air in Earth s atmosphere Unequal heating at Earth s surface Unequal pressure at Earth s surface Atmosphere tries to balance things out by redistributing heat Horizontal variation in pressure o Temperature rises warm air rises and pressure drops at surface Temperature decreases cold air sinks and pressure rises at surface o Earth is moving Wind Horizontal movement of air relative to Earth s surface Forces affecting wind gravity pressure gradient Coriolis force friction close to the surface 1 Forces of Gravity Not number one driving force No gravity no atmosphere no atmospheric pressure no imbalance no circulation These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute 2 Pressure Gradient Number one force Cold air sinks high pressure system Warm air rises low pressure system Atmospheric pressure weight of atmosphere over a given area Air moves from high pressure to low pressure 3 Coriolis Force Earth s rotation causes anything that flows across the surface of Earth wind ocean currents airplanes to deflect to the right in the Northern Hemisphere and also deflect to left in the Southern Hemisphere Causes winds to twist flow around pressure areas 4 Friction Reduces wind speed at Earth s surface Causes winds to spiral out from a high pressure area and into a low pressure area What causes friction The Earth s surface anything on the surface and stuff in the atmosphere Atmospheric Circulation 3 Cell circulation model o Hadley cell located at equator warm rising air Expansion and uplift of air at equator all flows to the poles Sinks at 30 degrees Some flows back to equator some flows to the poles o Polar cell located at the poles subsidence sinking of cold air at the poles Air flows to equator Warmed air rises at 60 degrees Some flows back to poles some to the equator o Ferrell cell located at mid latitude explanation for weather Collision of warm and cold air Caught between Hadley and Polar cells Air masses collide A lot of storms Surface Winds Variation in pressure creates prevailing winds Air moving from the poles to equator deflected easterlies tropics Air moving from equator to poles deflected westerlies mid latitude Jet Streams Sharp difference in temperature and lack of friction in the upper atmosphere above 300 500 meters at the surface creates strong winds that move from West to East Pressure Belts Equatorial low warm and rainy o Belt of low pressure warm rising air clouds condensation precipitation Inter Trop Convergence Zone ITCZ o coming together of trade winds at the equator Subtropical High cool and moist o Belt of low pressure warm and moist air meets cool air low pressure storms precipitation Polar High very cold and dry o High pressure cold dry air
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